Depron
Substitute - Foamboard

I first scratched the shiny
cardboard with 80 grit sandpaper to break any water seal.
I took foamboard and soaked it in water overnight in a
plastic garbage can liner.

This morning I just rubbed the
cardboard right off the foam. Now I have clean foam sheet
1/8" thick. I cannot tell any grain direction so I
will not be able to have the grain of the foam run
spanwise.

One piece 1250 mm by 800 mm is
what is called out in the drawing - that is 31.5" by
49.2"

Further Notes: My
stripped foamboard did not want to bend very easily to
form the leading edge. I added some thumbnail creases to
help it bend. This caused a small problem since the
material bent too much at the creases causing me to work
hard to get it to come out right.

I was initially concerned about
obtaining Depron or a substitute, but it is no longer a
problem. Foamboard is easily obtainable anywhere in the
USA and removing the cardboard skin is a simple
procedure.

I first cut out all the parts,
then sanded them, as suggested by Bob Harold, but then,
instead of putting them in a plastic bag, I put them in
my bathtub and covered them with water, weighing them
down with various heavy objects.

I wasn't as patient as Bob, so
after a couple of hours I removed the pieces and peeled
off the cardboard. Most of it peeled off easily, the
remainder I rolled off using the heel of my hand. The
whole process took about 15 minutes, no trouble at all,
really.

I also chose not to use spray
type adhesives, opting instead for my favourite contact
adhesive for foam - Dave Brown's Sorghum. This looks like
pure liquid latex rubber and provided it's used correctly
is the best adhesive for gluing foam. Simply apply it
evenly and thinly with a sponge to both surfaces, then
let it dry thoroughly, before joining the parts.

I trashed the first effort when I
had trouble making the LE bends. I was using 3/16th
foamboard. I went to another store and found 1/8th inch
foamboard ($4.57 for a 3'x4' piece) and it bent rather
easily

I had no problem removing the
cardboard using the two Bob's methods of soaking for a
couple of hours, and then removing the cardboard and
rubbing the glue off.

My Pibros came in at 8 ozs ready
to fly. I used 270 mah pack and FMA S-80 servos with a
FMA Micro Rx. If it flies as well as everyone says they
fly, I'll be really happy.

My 125% stock foamboard Pibros
had trouble staying up with the lower than normal winds.
I decided to make a lightweight Pibros, incorporating
some survivability measures that worked on its
predecessor.

I soaked and peeled the paper off
the foamboard and found that 60% of the weight is in the
thick paper "skin".

I planed a 3/16" dowel into
a "D" and stuck it on the L.E. to protect from
the rocks, then covered with clear packing tape, using a
minimal overlap. Final weight of the new airframe was 3.5
ounces, 8.5 ounces with radio gear for a wing loading of
3.8 oz/sq ft

I went up to our slope last nite
and the wind was about double what it has been. I tossed
the little Pibros off, expecting it to get blown around
like a potato chip. What resulted was about the most
fun a body can have for only $3!!!

With the elevon rate set to an
obscene level, it would do three consecutive rolls with
only a few feet of altitude loss. Inverted flight was
almost effortless. The vertical acceleration was amazing.
Trying tight loops into the wind from a low airspeed
resulted in a funny slow motion manoeuvre that
made me chuckle. Despite the wind speed, this thing
tracked rock stable, except for a little humpty-bump now
and then as it hit some shear or a gust. I attribute this
behaviour to its low drag
compared to conventional planes.

I admit now, that my doubts about
this thing being able to perform in strong wind were
unfounded, based on my experience with a lots of
conventional slopers!

Chris Handleywrites
Here is something I learnt whilst contemplating building
a Pibros.

Why waste good flying time
waiting for the foam board to delaminate in the bath. The
card lamination can simply and quickly removed using
lighter fuel (liquid form) by pouring a small amount onto
the card surface which is quickly rubbed in. Then give
one corner a good squirt and pick up the edge with a
finger nail and use the fuel again to work between the
foam and card. The card can them be peeled off in one
piece and repeat on the other side. To do this, a 100ml
can of fuel will be required and about 15 minutes of
time!

Mike Bailey writesI used 3/16" foamboard striped of its paper
for the top and bottom. I did not have enough for the
bottom so I used blue foam for the middle. It came out at
6.8 oz.

I had a cheap 3 channel radio so
set it up with separate elevator and ailerons.

I would use shoe-goo to
mount a tow hook. Apparently the foamboard doesn't like
it as it melted promptly. Not bad enough to really hurt
it because it stopped at the blue foam.

Depron
Substitute - "Coroplast"

Tord writes:
Sitting idle waiting for some varnish to dry I sat
fumbling a piece of coroplast ... An idea struck me, that
I want to test with you all (the idea is mine, but if you
build one for me it's all yours!):

Have any of you tried building a
Pibros from thin coroplast?

Take two squares of thin
Coroplast with DIAGONAL WEBBING or wells or channels -
you know what I mean!

Tape them side by side with
strapping tape or any other heavy duty tape. Now follow
regular pilbro practice using scrap pieces to fill the
innards.I don't think you can buy squares with diagonal
channels, so You will have a lot of scrap - remember to
place the channels on the inner pieces spanwise, if
possible!

...When I did a density
comparison, I was shocked to find that my
"standard" (?) coroplast weighs 5 times what
the foam core does.

In view of the fact that the
Pibros is so much fun because it's light, so I've benched
the idea for now. Maybe a part coroplast part foam
construction? My coroplast is about 3mm thick, maybe you
have a thinner variety?

VH-grade
polystyrene

Before I found a handy source of
foamboard, my first Pibros was constructed from a denser
form of polystyrene foam known here as VH Grade
polystyrene. It's appears almost the same density as Blue
foam, but is much lighter.. I skimmed a few 3mm sheets
off a block using 5mm piano wire either side to run the
wire across. The wire of course melts a little more foam
so you end up with an approximate 3mm sheet..

When sprayed with 3M adhesive it
becomes remarkably flexible,and construction is much the
same as normal,but use a little more care to avoid
dinging the foam. Sand the leading edge with a fine
sanding block to complete it... A thin piece of coroplast
from a real estate advertising sign make a sturdy yet
light vertical stab...

I also covered mine with a very
light transparent packing tape similar to that used on
the Zagi (mainly so I could see it) and it has proved
just as agile and resistant to damage as the foamboard
one!

Using this method,I guess normal
polystyrene may work,no harm in trying if you have a few
bit's lying around (doesn't everyone?) Go to it!

Tim Wood
writes:

My method using 20mm polystyrene is not really
cutting - more like melting :)Lay
the basic 800x400 triangle flat. Then get a piece of greaseproof
paper and lay it over the triangle. Using a hot iron you can melt the
polystyrene into shape (the paperprotects
the iron - as wife wouldn't be too happy). Start at the middle(roughly)
and work back to the TL applying more pressure here will melt acurve - and so on. It really works try it - it
make making these sorts of wingsimple -
you need to sand it all down after but its neat ! and it makes thefoam stronger as you are melting and compressing
it together.I am going to try this method
for making a proper electric trainer next.

Depron
Substitute - "Amocor"

Re Depron, I have found a source
for this material under the name of AMOCOR P14 FANFOLD it
comes in a 4 X 50 foot bundle, and in the Lowes hardware
store here in Pensacola, FL, costs $33.85. The company's
address is

Installing
a Towhook

The Pibros flew well from a Zip
start. I taped on a hook mounted to a 2'"by 1"
piece of 1/16" plywood, located 1/2" ahead of
the C.G.

I let two of my soaring buddies
fly it so they now have the Pibros fever!

Bob Botha writes:The short highstart that I have been using was
originally intended for launching HLGs and comprises of
10 feet of 1/8" ID 1/16" wall thickness
surgical tubing, joined to 18 feet of 20lb fishing line.

With the towhook located about
1/2" in front of the CG it shoots off at about a 45
deg. angle and continues to about 200-300 ft. - a whole
lot higher than any HLG would go!

To attach the towhook, I recessed
a 2"x1/2"x1/4" piece of hardwood into the
foam just ahead of the CG. A modified cup hook was
screwed into this. I made the fin out of solid foamboard
(the cardboard left on) and epoxied it into a slot. This
was just as well because the fin is the only
"handle" to hang onto when pulling it back on
the zipstart. I had visions of being left with the fin in
my hand while the glider took off without it, but so far
it has held on!

Possibly making a fin that
extends through the wing to make a small sub fin would
enable one to grip it there for a more normal above the
shoulder launch.

Mark Mech writes: Since finishing the proto Avro/Pibros I've flown
it more in a month than I've flown anything the last
year. I can get 150ft. off of my 20ft. bungee and even
though the flights are only a couple minutes. I don't
have to walk far to re launch, so I get a lot of flights
in short session.

Jim Keller writes:I tried launching my Pibros using my light
Highstart. I taped a hook about an inch ahead of the
c.g., and gave a 30% pull on the line for a test hop and
away she went. Straight into the ground.

...I then tried releasing it with
about a 30 degree angle of attack. This proved to be the
thing, as it climbed out and reached about 80 feet or so
and popped off, giving me about a 20 second flight -
enough for a quick victory roll and a loop, then a gentle
glide for a landing at my feet. Variations on this theme
resulted in flights of higher launch altitude but about
the same duration

On one launch, I added more than
obscene amount of tension. I must have not added the
angle of attack part. It left my hand like a Sidewinder
off an F-16's wingtip, struck the ground about 20 feet
away, then cartwheeled seemingly forever. The only damage
was a slightly rumbled beak and the battery pack fell
out. I replace the battery and flew again without
touching a thing.

Observations: Pibros is quick on
a highstart. The elevon trim has to be dead neutral, or
you'll instantly have foamboard all over the place.

Pibros is a great little sloper,
but definitely not a thermal duration competitor.

Chris Erikson writes:
Boy I'll bet some folks are getting sick of these endless
Pibros posts.... But what the heck, it's just so darned
fun!

...I realized I'd never tried the
cat launches everybody's been raving about. We dug in my
field box and came up with 20 1/2" x 3" rubber
bands. We daisychained them together, then tied the last
one on the end of a stout stick. I used a piece of music
wire for a towhook about 2" in front of the CG.

My friend held the stick up at
shoulder height, and I held the Pib by it's well anchored
coroplast tail. I stretched back about 10 feet, lowered
it till we had about 45 degrees of launch angle, and let
fly. Unreal. The rubber bands have plenty of kick to
accelerate this light plane, it would make this great
"whoosh" noise and knife up into the sky to
about 75-100 feet, I'd guess.

The sight of this tiny delta
screaming up into the sky and not slowing down much had
us both practically rolling on the dirt, I almost crashed
on the first flight cause I was laughing so hard I
couldn't see straight. If you can't get any tubing just
try some hefty rubber bands, it works great!

...I haven't flown any of my
other planes since I built this stupid thing. What's
wrong with me?

Geez, we finally got the Pibros
to hi-start. Gawd almighty !!. Used a 6 foot length of
3/16 surgical tubing, 20 feet of line with a couple of
streamers attached about 18 inches below the tow ring to
help pull off the ring (TOTALLY unnecessary - trust me).

6 backward steps for tension and
pointed it at about 30 degrees. Did I mention that this
is a two man operation ? The launcher needs to hold the
plane with both hands by the LE and the Pilot needs to
stand behind the launcher to tell him either more up or
more down. About 30 degrees seems to be cool.

One final waggle to be sure that
you remembered to plug in the battery and tell the
launcher "anytime" (I assume this is similar to
a carrier pilot saluting the catapult officer when
everything is green - there ain't much left to do except
hang on and pray fervently).

HOLY MOLY what a launch !!! The
darn thing accelerates to about mach 4.5 (I exaggerate -
but not much) in three and a half feet and ROCKETS up the
line. It was shedding the tow ring at about 15 feet but
that didn't seem to slow her down much. Launches were
phenomenal !!! She just kept climbing to around 100 to
125 feet.

After the peak, it was just float
around in a big circle, right or left or loop right at
the top and land at your feet.

Next time I'm going to try a roll
or two on the way up the zoom and I've also got some
longer rubber and line. I'd like to try to keep her on
the line a little longer. The streamers were not needed
at all. The line pulled off with no problems but they
might be needed with the longer line.

BTW: NO up or control inputs are
needed at launch. Just make sure that the Pibros glides
straight and level BEFORE you try the hi-start.

Have been launching it with a 25
foot piece of surgical tubing and a 30' piece of 50 LB.
string with a welded metal ring. I tie it to a park bench
and have at it 150 feet may be an exaggeration but not
that much. The fun begins 50 feet after release. The
rolls and the loops, both inside and outside are
incredible. I launched this last weekend over fifty
times, rolling out inverted, then giving full down
elevator doing an inverted inside loop, then circle
around and play with the light air and a landing. Hook it
up and go at it again!.

I too built a larger version, 40
inches, to use standard gear. It flies equally as well. I
flew it last week at the beach in cold winds and blowing
sand. Great in medium wind off the cliffs.

Euro-Pibros
from NSP

The Euro-Pibrosfrom NSP
weighs 7.3 ounces all up with a 250 mah square pack and 2
S-133 Futaba micro servos and a Hitec 535 receiver.

Elevon pushrods are 1/16"
music wire about 7 inches on each with a brass coupler
and brass Sullivan clevis at the servo end and a Z-bend
at the elevon horn which is a Goldberg large nylon horn
which I mounted to the elevon with hot melt glue.

On my next ship I plan to use
1/16" homemade elevon horns epoxied into the elevons
with 5 minute epoxy in a hacksawed slot. I think this
will provide a more durable horn setup. make sure both
horns have identical holes and are located in EXACTLY the
same position relative to the hinge centerline, both in
the vertical and horizontal planes.

Battery pack, receiver and servos
are held in with Scotch 2" wide filament packing
tape that I picked up at Office Max. I traced the servo,
battery and receiver locations on the top surface once I
had everything in position to balance the ship at 208 mm
from the apex. Then I routed out the "pockets"
with my Dremel tool with the router attachment set at
about 1/2" deep and carefully opened up the pockets
till the respective components fit with a somewhat tight
fit. It is not real hard, in fact I did mine at the motel
room during the Nats..... ;-))

I expect this one to come close
to the 7.3 ounce finished weight. Balance is critical. I
balanced mine at 208 mm from the apex of the delta. The
plans call for 210 mm. There is not much latitude here.
Stick to what Marcel says.

Initial flying setup should be
CONSERVATIVE. I really bashed mine, thinking I could
handle the 45 degree elevon throws. This thing is a
handful with 45 degree throws. Start with 20 degrees and
go from there. Hand toss it a few times, dialing in some
up trim. Mine took about 1/8" of up to give a
reasonable glide. Zip starts are flat and fast. Keep the
stick inputs minimal till you get the hang of it. A 20
pace zip start will launch it at a 10 degree up angle at
40 mph. Keep the speed up for 250 feet or so and make a
GENTLE 180 degree turn back to you, KEEPING THE SPEED
UP!!! If you give it too much up, it simply raises its
nose and stops flying! It will then mush to the ground. I
am not anywhere near an expert pilot, but I got the hang
of it quickly.

Trimming
and Flying

[My Pibros] weighs 9oz and flies
beautifully, except it won't loop! One thing I
discovered, though, was that it is not that touchy about
CG position. I experimented by moving it back and forth
and other than having to adjust the elevator neutral
position, it remained quite stable throughout the range,
but still wouldn't loop! Possibly if it were heavier it
would have the necessary momentum to carry it through,
but then its light wind attributes would be lost. Oh,
well, you can't have everything, I guess! All I can say
is that I've had a lot of fun with that $5 glider.

Bamboo
strengtheners

Try strengthening the leading
edge by taping bamboo meat skewers from the front to
about 10 cm back. bamboo is very hard and yet
exceptionally light ( a natural composite material) and
can be found in any supermarket. This stiffens up the
front end and helps to stop the crumple problem.

I think I could increase the wing
area to get a lower wing loading, I am going to try a 25%
increase, when I get some building time in the next week
or so. I have not flown this one yet, but I have flown
the 5.5oz one I build with 100mah batteries and wire
rods. Penetrates and flies in as normal, incredibly fast
elevator response, flying to 20+mph winds no issues.

Having always being interested in
the Pibros I built a 1 meter span version to
take standard radio gear.

I got some company in Cape Town
to cut me 4 mm thick foam sheets and away I when as per
the normal instructions.

I added a bit of strapping tape
in a X shape to the bottom of the Pibros (just to put my
mind at ease).

Flying the Pibros was great, its
easy , very stable yet has a very impressive roll rate -
not bad for about R10-50 and some change!!!! Hovers are
nice and easy - inverted or 'normal' flying. Maybe the
tail should be made of coroplast for that occasional
combat hit!

I did find that the 'elevator'
trim seem to change through the flight with more up trim
being required as the flight progresses - any comments
from experienced Pibros flyers would be welcome to remedy
this one and only problem. Well that it - just had to let
any doubters know - standard gear in a 1m PIBROS , no
problem.

I built my Pibro 50% larger with
foam board found in the US in craft shops. Total weight
was 21 oz which comes to 5 oz/sq. ft wing loading. I had
an old radio so I had divided the elevons into ailerons
(outboard) and an elevator (centre).

First couple flights were not too
good because of pilot error but after a couple minor
dents the plane flew great. Next time a little more wind
up the slope is needed; I only had 5 mph puffs.

In scaling up I added TWO more
layers of triangular foam sheets so that the delta wing
thickness was scaled 50% more also. Great
site....creative design - Thanks to the inventor Marcel!

Comes in at 22oz with a 1.2m
wingspan. Since I was using twice the normal thickness of
foam, I took Richard Frawleys advice and cut sections
out. But, I didn't think to do this until the airframe
was done and I discovered it weighed in at over 16oz. So
I cut triangular sections out of the finished frame. Cut
all the way thru and then cover the holes with ordinary
packing tape (like some use to cover EPP models). Then I
heat shrunk (?) the tape to get it nice and smooth.

Final frame weight, 14 oz. Looks
similar to a "built-up" covered stab. Only had
5 mph breeze to try it out. No long slope flights today.
Also gave the histart a whirl. 33' of 1/8" ID
tubing, 60' of cord. Off like a rocket to 150 - 200 ft.
Not too bad. I think it's too heavy for its scale.

I've got a ton of this "pink
foam" left, so the next project is to up-scale the
Pibros to 2 meters! This should be ample surface area for
my standard gear, plus I want to thermal this puppy!
Should help sloping on those slow wind days, too. ;-)